Contributing roles of mitochondrial dysfunction and hepatocyte apoptosis in liver diseases through oxidative stress, post-translational modifications, inflammation, and intestinal barrier dysfunction.

This review provides an update on recent findings from basic, translational, and clinical studies on the molecular mechanisms of mitochondrial dysfunction and apoptosis of hepatocytes in multiple liver diseases, including but not limited to alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD), and drug-induced liver injury (DILI). While the ethanol-inducible cytochrome P450-2E1 (CYP2E1) is mainly responsible for oxidizing binge alcohol via the microsomal ethanol oxidizing system, it is also responsible for metabolizing many xenobiotics, including pollutants, chemicals, drugs, and specific diets abundant in n-6 fatty acids, into toxic metabolites in many organs, including the liver, causing pathological insults through organelles such as mitochondria and endoplasmic reticula. Oxidative imbalances (oxidative stress) in mitochondria promote the covalent modifications of lipids, proteins, and nucleic acids through enzymatic and non-enzymatic mechanisms. Excessive changes stimulate various post-translational modifications (PTMs) of mitochondrial proteins, transcription factors, and histones. Increased PTMs of mitochondrial proteins inactivate many enzymes involved in the reduction of oxidative species, fatty acid metabolism, and mitophagy pathways, leading to mitochondrial dysfunction, energy depletion, and apoptosis. Unique from other organelles, mitochondria control many signaling cascades involved in bioenergetics (fat metabolism), inflammation, and apoptosis/necrosis of hepatocytes. When mitochondrial homeostasis is shifted, these pathways become altered or shut down, likely contributing to the death of hepatocytes with activation of inflammation and hepatic stellate cells, causing liver fibrosis and cirrhosis. This review will encapsulate how mitochondrial dysfunction contributes to hepatocyte apoptosis in several types of liver diseases in order to provide recommendations for targeted therapeutics.

Genetic variations in CYP2A6, CYP2E1, GSTM1, GSTT1 genes and the risk of Nasopharyngeal carcinoma in North African population.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a multifactorial malignancy associated with both genetic and environmental factors. Polymorphic deletions of the phase I and phase II genes involved in the detoxification of potential carcinogens may be a risk factor for nasopharyngeal carcinoma. In this study, we investigated the relationship between CYP2E1 (rs3813867), CYP2A6, GSTM1(rs1183423000) and GSTT1(rs1601993659) gene variations and NPC risk in North African countries with the highest incidence of NPC (Morocco, Algeria and Tunisia). and the evaluation of the potential use of these variants as potential biomarkers for NPC management. METHODS: A total of 600 NPC cases and 545 controls frequency-matched on ethnicity, sex, age and childhood household type, were recruited from three North African countries (Morocco, Algeria and Tunisia) and analysed. Genotyping of CYP2A6 and CYP2E1(rs3813867) was performed by polymerase chain reaction restriction (PCR)-fragment length polymorphism (RFLP) analysis and the GSTM1 (rs1183423000) and GSTT1(rs1601993659) genetic variations were evaluated using the PCR technique. RESULTS: The genotype distributions of CYP2E1(rs3813867), CYP2A6, GSTM1(rs1183423000) and GSTT1(rs1601993659) genotypes did not differ significantly among NPC cases and controls (p > 0.05). Furthermore, our data did not reveal any association with smoking and the studied variants, even when the samples were stratified by the duration period of smoking. CONCLUSION: In this large studied North African population, our findings suggest that the functional CYP2E1, CYP2A6, GSTM1 and GSTT1 variations did not influence NPC susceptibility.

Interaction between fatty acid oxidation and ethanol metabolism in liver.

Fatty acid oxidation (FAO) releases the energy stored in fat to maintain basic biological processes. Dehydrogenation is a major way to oxidize fatty acids, which needs NAD+ to accept the released H+ from fatty acids and form NADH, which increases the ratio of NADH/NAD+ and consequently inhibits FAO leading to the deposition of fat in the liver, which is termed fatty liver or steatosis. Consumption of alcohol (ethanol) initiates simple steatosis that progresses to alcoholic steatohepatitis, which constitutes a spectrum of liver disorders called alcohol-associated liver disease (ALD). ALD is linked to ethanol metabolism. Ethanol is metabolized by alcohol dehydrogenase (ADH), microsomal ethanol oxidation system (MEOS), mainly cytochrome P450 2E1 (CYP2E1), and catalase. ADH also requires NAD+ to accept the released H+ from ethanol. Thus, ethanol metabolism by ADH leads to increased ratio of NADH/NAD+, which inhibits FAO and induces steatosis. CYP2E1 directly consumes reducing equivalent NADPH to oxidize ethanol, which generates reactive oxygen species (ROS) that lead to cellular injury. Catalase is mainly present in peroxisomes, where very long-chain fatty acids and branched-chain fatty acids are oxidized, and the resultant short-chain fatty acids will be further oxidized in mitochondria. Peroxisomal FAO generates hydrogen peroxide (H2O2), which is locally decomposed by catalase. When ethanol is present, catalase uses H2O2 to oxidize ethanol. In this review, we introduce FAO (including α-, ß-, and ω-oxidation) and ethanol metabolism (by ADH, CYP2E1, and catalase) followed by the interaction between FAO and ethanol metabolism in the liver and its pathophysiological significance.

CYP2E1 deficit mediates cholic acid-induced malignant growth in hepatocellular carcinoma cells.

BACKGROUND: Increased level of serum cholic acid (CA) is often accompanied with decreased CYP2E1 expression in hepatocellular carcinoma (HCC) patients. However, the roles of CA and CYP2E1 in hepatocarcinogenesis have not been elucidated. This study aimed to investigate the roles and the underlying mechanisms of CYP2E1 and CA in HCC cell growth. METHODS: The proteomic analysis of liver tumors from DEN-induced male SD rats with CA administration was used to reveal the changes of protein expression in the CA treated group. The growth of CA-treated HCC cells was examined by colony formation assays. Autophagic flux was assessed with immunofluorescence and confocal microscopy. Western blot analysis was used to examine the expression of CYP2E1, mTOR, AKT, p62, and LC3II/I. A xenograft tumor model in nude mice was used to examine the role of CYP2E1 in CA-induced hepatocellular carcinogenesis. The samples from HCC patients were used to evaluate the clinical value of CYP2E1 expression. RESULTS: CA treatment significantly increased the growth of HCC cells and promoted xenograft tumors accompanied by a decrease of CYP2E1 expression. Further studies revealed that both in vitro and in vivo, upregulated CYP2E1 expression inhibited the growth of HCC cells, blocked autophagic flux, decreased AKT phosphorylation, and increased mTOR phosphorylation. CYP2E1 was involved in CA-activated autophagy through the AKT/mTOR signaling. Finally, decreased CYP2E1 expression was observed in the tumor tissues of HCC patients and its expression level in tumors was negatively correlated with the serum level of total bile acids (TBA) and gamma-glutamyltransferase (GGT). CONCLUSIONS: CYP2E1 downregulation contributes to CA-induced HCC development presumably through autophagy regulation. Thus, CYP2E1 may serve as a potential target for HCC drug development.

Binge alcohol induces NRF2-related antioxidant response in the skeletal muscle of female mice.

BACKGROUND: Chronic alcohol enhances oxidative stress, but the temporal response of antioxidant genes in skeletal muscle following a binge drinking episode remains unknown. METHODS: Experiment 1: C57BL/6Hsd female mice received an IP injection of saline (CON; n = 39) or ethanol (ETOH; n = 39) (5 g/kg). Gastrocnemius muscles were collected from baseline (untreated; n = 3), CON (n = 3), and ETOH (n = 3) mice every 4 h for 48 h. Experiment 2: Gastrocnemius muscles were collected from control-fed (CON-FED; n = 17), control-fasted (CON-FAST; n = 18), or alcohol-fed (ETOH-FED; n = 18) mice every 4hrs for 20hrs after saline or ethanol (5 g/kg). RESULTS: EtOH enhanced Superoxide dismutase 1 (Sod1) and NADPH Oxidase 4 (Nox4) from 24 to 48hr after the binge, while Sod2 and Nox2 were suppressed. Nuclear factor erythroid-derived 2-like 2 (Nrf2) and Kelch-like ECH-associated protein 1 (Keap1) increased 12hrs after intoxication. Cytochrome P450 oxidoreductase (Por), Heme oxygenase 1 (Ho1), Peroxiredoxin 6 (Prdx6), Glutamate-cysteine ligase catalytic subunit (Gclc), Glutamate-cysteine ligase modifier subunit (Gclm), and Glutathione-disulfide reductase (Gsr) were increased by ETOH starting 12-16hrs post-binge. Fasting had similar effects on Nrf2 compared to alcohol, but downstream targets of NRF2, including Por, Ho1, Gclc, and Gclm, were differentially altered with fasting and EtOH. CONCLUSION: These data suggest that acute alcohol intoxication induced markers of oxidative stress and antioxidant signaling through the NRF2 pathway and that there were effects of alcohol independent of a possible decrease in food intake caused by binge intoxication.

Transgenic expression of human cytochrome P450 2E1 in C. elegans and rat PC-12 cells sensitizes to ethanol-induced locomotor and mitochondrial effects.

Chronic alcohol (ethanol) use is increasing in the United States and has been linked to numerous health issues in multiple organ systems including neurological dysfunction and diseases. Ethanol toxicity is mainly driven by the metabolite acetaldehyde, which is generated through three pathways: alcohol dehydrogenase (ADH2), catalase (CAT), and cytochrome P450 2E1 (CYP2E1). ADH2, while the main ethanol clearance pathway in the liver, is not expressed in the mammalian brain, resulting in CAT and CYP2E1 driving local metabolism of ethanol in the central nervous system. CYP2E1 is known to generate reactive metabolites and reactive oxygen species and localizes to the mitochondria (mtCYP2E1) and endoplasmic reticulum (erCYP2E1). We sought to understand the consequences of mtCYP2E1 and erCYP2E1 in the nervous system during acute ethanol exposure. To answer this question, we generated transgenic Caenorhabditis elegans roundworms expressing human CYP2E1 in the mitochondria, endoplasmic reticulum, or both and exposed them to ethanol. We found that at lower concentrations, wild-type and mtCYP2E1-expressing worms had a small but significant inhibition of locomotion, whereas the erCYP2E1-expressing worms showed protection from this inhibition. At higher doses, all strains had reduced locomotion, but the erCYP2E1-expressing worms recovered faster than wild-type controls. CYP2E1 expression, regardless of organellar targeting, reduced mitochondrial respiration in response to ethanol. Similarly, transgenic expression of CYP2E1 in either organelle in PC-12 rat neuronal cell lines sensitized them to ethanol-induced cell death. Together, these findings suggest that subcellular localization of CYP2E1 impacts behavioral effects of ethanol and should be further studied in the mammalian central nervous system.

Environmentally Persistent Free Radicals stimulate CYP2E1-mediated generation of reactive oxygen species at the expense of substrate metabolism.

Environmentally persistent free radicals (EPFRs) are a recently recognized component of particulate matter that cause respiratory and cardiovascular toxicity. The mechanism of EPFR toxicity appears to be related to their ability to generate reactive oxygen species (ROS), causing oxidative damage. EPFRs were shown to affect P450 function, inducing the expression of some forms through the Ah receptor. However, another characteristic of EPFRs lies in their ability to inhibit P450 activities. CYP2E1 is one of the P450s that is inhibited by EPFR (MCP230) exposure. As CYP2E1 is also known to generate ROS, it is important to understand the ability of EPFRs to influence the function of this enzyme and to identify the mechanisms involved. CYP2E1 was shown to be inhibited by EPFRs, and to a lesser extent by non-EPFR particles. As EPFR-mediated inhibition was more robust at subsaturating NADPH-cytochrome P450 reductase (POR) concentrations, disruption of POR·CYP2E1 complex formation and electron transfer were examined. Surprisingly, neither complex formation nor electron transfer between POR and CYP2E1 were inhibited by EPFRs. Examination of ROS production showed that MCP230 generated a greater amount of ROS than the non-EPFR CuO-Si. When a POR/CYP2E1-containing reconstituted system was added to the pollutant-particle systems there was a synergistic stimulation of ROS production. The results indicate that EPFRs cause inhibition of CYP2E1-mediated substrate metabolism, yet do not alter electron transfer and actually stimulate ROS generation. Taken together, the results are consistent with EPFRs affecting CYP2E1 function by inhibiting substrate metabolism and increasing the generation of ROS. Significance Statement Environmentally persistent free radicals affect CYP2E1 function by inhibition of monooxygenase activity. This inhibition is not due to disruption of the POR·CYP2E1 complex or inhibition of electron transfer, but due to uncoupling of NADPH and oxygen consumption from substrate metabolism to the generation of ROS. These results show that EPFRs block the metabolism of foreign compounds, and also synergistically stimulate the formation of reactive oxygen species that lead to oxidative damage within the organism.

The hepatoprotective effect of 4-phenyltetrahydroquinolines on carbon tetrachloride induced hepatotoxicity in rats through autophagy inhibition.

BACKGROUND: The liver serves as a metabolic hub within the human body, playing a crucial role in various essential functions, such as detoxification, nutrient metabolism, and hormone regulation. Therefore, protecting the liver against endogenous and exogenous insults has become a primary focus in medical research. Consequently, the potential hepatoprotective properties of multiple 4-phenyltetrahydroquinolines inspired us to thoroughly study the influence of four specially designed and synthesized derivatives on carbon tetrachloride (CCl4)-induced liver injury in rats. METHODS AND RESULTS: Seventy-seven Wistar albino male rats weighing 140 ± 18 g were divided into eleven groups to investigate both the toxicity profile and the hepatoprotective potential of 4-phenyltetrahydroquinolines. An in-vivo hepatotoxicity model was conducted using CCl4 (1 ml/kg body weight, a 1:1 v/v mixture with corn oil, i.p.) every 72 h for 14 days. The concurrent treatment of rats with our newly synthesized compounds (each at a dose of 25 mg/kg body weight, suspended in 0.5% CMC, p.o.) every 24 h effectively lowered transaminases, preserved liver tissue integrity, and mitigated oxidative stress and inflammation. Moreover, the histopathological examination of liver tissues revealed a significant reduction in liver fibrosis, which was further supported by the immunohistochemical analysis of α-SMA. Additionally, the expression of the apoptotic genes BAX and BCL2 was monitored using real-time PCR, which showed a significant decrease in liver apoptosis. Further investigations unveiled the ability of the compounds to significantly decrease the expression of autophagy-related proteins, Beclin-1 and LC3B, consequently inhibiting autophagy. Finally, our computer-assisted simulation dockingonfirmed the obtained experimental activities. CONCLUSION: Our findings suggest that derivatives of 4-phenyltetrahydroquinoline demonstrate hepatoprotective properties in CCl4-induced liver damage and fibrosis in rats. The potential mechanism of action may be due to the inhibition of autophagy in liver cells.

Different ethanol exposure durations affect cytochrome P450 2E1-mediated sevoflurane metabolism in rat liver.

BACKGROUND: Chronic alcohol users often exhibit an increased minimum alveolar concentration (MAC) of sevoflurane, yet the specific mechanism remains unclear. It has been reported that ethanol exposure can upregulate the protein expression and enzyme activity of cytochrome P450 2E1 (CYP2E1). CYP2E1 is a key enzyme that converts 2-5% of sevoflurane into equimolar amounts of hexafluoroisopropanol (HFIP) and F-. This study aims to explore whether ethanol exposure could alter sevoflurane metabolism through CYP2E1 modulation, potentially explaining the increased MAC observed in alcohol users. METHODS: Eighty adult male Sprague-Dawley (SD) rats were randomly divided into two groups and received either 50% ethanol (dose: 3 g/kg) or 0.9% saline twice daily by gavage. After 1, 2, 3, and 4 weeks of gavage, ten rats were randomly selected from each group to undergo 1-hour anesthesia with 2.3% sevoflurane. Blood samples were collected after anesthesia to measure the concentration of free HFIP using gas chromatography. Additionally, the left lobe tissue of the liver was collected for the analysis of CYP2E1 protein expression by Western blot and CYP2E1 enzyme activity by colorimetric assay. Correlations between these parameters were analyzed using Pearson's correlation. RESULTS: In the ethanol group, CYP2E1 expression, activity, and the concentration of free HFIP were significantly higher at all time points compared to the control group (P < 0.05), except for protein expression in the first week (P > 0.05). Within-group comparisons indicated no significant changes in any of the parameters for the control group (P > 0.05). In the ethanol group, there was no difference in free HFIP concentration between the first and second weeks (P > 0.05), but a significant increase was observed in the third and fourth weeks (P < 0.01); protein expression and enzyme activity significantly varied over time, especially showing a notable increase from the first to the third and fourth weeks (P < 0.05). Correlation analysis revealed strong positive correlations between free HFIP concentration and CYP2E1 activity (r = 0.7898), free HFIP concentration and CYP2E1 expression (r = 0.8418), and CYP2E1 activity and expression (r = 0.8740), all with P < 0.001. CONCLUSIONS: Ethanol exposure increased both the expression and enzymatic activity of CYP2E1, consequently enhancing the metabolism of sevoflurane.

Species-specific metabolism of triphenyl phosphate and its mono-hydroxylated product by human and rat CYP2E1 and the carp ortholog.

Organophosphorus flame retardants (PFRs) are a class of flame retardants and environmental pollutants with various biological effects. Recentstudies have evidenced activation of some PFRs by human CYP enzymes (including CYP2E1) for genotoxic effects. However, the activity of CYPs in fish species toward PFR metabolism remains unclear. This study was aimed on comparing the metabolism of triphenyl phosphate (TPHP) and 4-OH-TPHP in human, rat, and common carp, and the involvement of human CYP2E1 and its orthologs in the metabolism, by using fomepizole (4-MP, CYP2E1 inhibitor) as a modulator, in silico molecular docking and dynamics analyses. The rate of TPHP metabolism was apparently faster with human and rat, microsomes than with fish microsomes, the major metabolites were phosphodiester and hydroxylated phosphate, with 30-80 % of TPHP forming unidentified metabolites in the system of each species. 4-OH-TPHP was readily metabolized by both human and rat microsomes, whereas it was hardly metabolized in carp assays. Meanwhile, with 4-MP the transformation of TPHP to 4-OH-TPHP was enhanced in the human/rat systems while suppressed in the carp system. Moreover, the formation of unidentified metabolites in human and rat systems was mostly inhibited by 4-MP. Through molecular dynamics analysis TPHP and its primary metabolites showed high affinity for human and rat CYP2E1, as well as the carp ortholog (CYP2G1-like enzyme), however, the 4-OH-TPHP bond to the latter was too far from the heme to permit a biochemical reaction. This study suggests that the metabolism/activation of TPHP might be favored in mammals rather than carp, a fish species.

CYP2E1 triggered GRP78/ATF6/CHOP signaling axis inhibit apoptosis and promotes progression of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the leading cause of cancer-related death worldwide. Cytochrome P450 2E1 (CYP2E1) is an enzyme, primarily involved in the metabolism of xenobiotics and procarcinogens. The present study was designed to investigate the potential role of CYP2E1 triggered endoplasmic reticulum stress in the progression of HCC through inhibition of apoptosis. In vitro CYP2E1 promotes HepG2 cell migration, reduced chromatin condensation, enhanced intracellular ROS accumulation and induce cell cycle progression. Conversely this effect was averted by CYP2E1 siRNA, selective inhibitor Diallyl sulphide (DAS) and antioxidants (vitamin C and E). In vivo Diethylnitrosamine (DEN) induced HCC rats showed decreased body weight and increased relative liver weight. Moreover, macro trabecular-massive HCC (MTM-HCC) histological subtyping showed pathological features like well-differentiated tumors, micro-trabecular and pseudo glandular patterns, megakaryocytes and cholestasis. Masson's trichrome staining revealed an intensive accumulation of collagen fibers in the extracellular matrix (ECM). Increased CYP2E1, VEGF and PCNA enhance the carcinogenicity as revealed in immunohistochemistry results. Immunoblot analysis showed reduced expression of copper-zinc superoxide dismutase (CuZnSOD) and manganese superoxide dismutase (MnSOD) in cytosolic as well as mitochondrial fraction of rat liver tissue respectively. Also, increased level of CYP2E1 stimulated the upregulation of unfolded proteins response (UPR) and ER stress-related proteins such as Glucose regulatory protein 78 (GRP78), activating transcription factor 6 (ATF6) and CCAAT enhancer-binding protein (C/EBP) homologous protein (CHOP). Meanwhile, CYP2E1 stimulated ER-stress reduces BCL2 and downregulates the cleaved caspase 3 thus suppresses apoptosis. in. Furthermore, immunofluorescence revealed increased expression level of α-SMA in the HCC rat liver tissue. The level of CYP2E1 mRNA was significantly increased. Altogether, these findings indicate that CYP2E1 has a dynamic role in the pathogenesis of HCC and might be a budding agent in liver carcinogenesis therapy.

Toxic effect of carpet dust on the biochemical indices and histological structure of the lung in rats: the potential role of cytochrome P450 2E1 and extracellular signal-regulated kinase/mitogen-activated protein kinase pathways.

Background: Carpet dust exposure in the carpet industry causes various respiratory hazards that lead to permanent loss of lung function. This study investigated the potentially toxic effects of knotted and tufted carpet dust on rat lungs and the possible involvement of cytochrome P450 2E1 (CYP2E1) and extracellular signal-regulated kinase/mitogen-activated protein kinase (ERK/MAPK) pathways in the induced toxicity, as well as histological changes in the lung induced by carpet dust.Methods: This study divided 48 adult rats into six groups: group I was the control group, group II (vehicle group) received phosphate buffer saline (50 µL/rat), groups III and IV received knotted dust (2.5 and 5 mg/kg, respectively), and groups V and VI received tufted dust (2.5 and 5 mg/kg, respectively). All treatments were intranasally administered once a day for 7 days.Results: Both dust types significantly decreased the lung content of GSH compared with the control. Significantly elevated malondialdehyde (MDA) and nitric oxide (NO) lung contents were observed with an increased CYP2E1, interleukin (IL)-6, nuclear factor kappa B (NF-κß), and ERK/MAPK. The histological lung structure was moderately affected with a moderately increased number of CD68-positive macrophages in the lung parenchyma of knotted dust-exposed rats, whereas tufted dust exposure severely affected the lung tissue with significantly increased CD68-positive macrophages.Conclusions: Carpet dust exposure could induce oxidative stress and inflammatory response in the lung tissue via induction of CYP2E1 that stimulates ERK/MAPK signalling pathway proteins, resulting in elevated MDA, NO and IL-6 levels in the lung tissue with suppressed GSH content. Tufted dust could possess a more toxic response than knotted ones.

CYP2E1 C-1054T and 96-bp I/D genetic variations and risk of gestational diabetes mellitus in chinese women: a case-control study.

BACKGROUND: Cytochrome P450 2E1 (CYP2E1) plays a key role in the metabolism of xenobiotic and endogenous low-molecular-weight compounds. This study aimed to determine if the genetic variations of 96-bp insertion/deletion (I/D) and C-1054T (rs2031920) in CYP2E1 were associated with the risk of gestational diabetes mellitus (GDM). METHODS: CYP2E1 polymorphisms were genotyped in a case-control study of 1,134 women with uncomplicated pregnancies and 723 women with GDM. The effects of genotype on the clinical, metabolic, and oxidative stress indices were assessed. RESULTS: The CYP2E1 C-1054T variant was associated with an increased risk of GDM based on the genotype, recessive, dominant, and allele genetic models (P < 0.05). The TT + CT genotype remained a significant predictive factor for GDM risk after correcting for maternal age and pre-pregnancy body mass index (OR = 1.277, 95% CI: 1.042-1.563, P = 0.018). Moreover, fasting insulin concentrations and homeostatic model assessment of insulin resistance were significantly higher in GDM patients carrying the T allele than in those with the CC genotype (P < 0.05). Furthermore, the combined genotype II + ID/TT + CT of the 96-bp I/D and C-1054T polymorphisms further increased the risk of GDM when the combined genotype DD/CC was set as the reference category (OR = 1.676, 95% CI: 1.182-2.376, P = 0.004). CONCLUSIONS: The T allele of the C-1054T polymorphism and its combination with the I allele of the 96-bp I/D variation in CYP2E1 are associated with an increased risk of GDM in the Chinese population. The - 1054T allele may be associated with more serious insulin resistance in patients.

Association between CYP2E1 C-1054T and 96-bp I/D genetic variations and the risk of polycystic ovary syndrome in Chinese women.

PURPOSE: To investigate the association of cytochrome P450 2E1 (CYP2E1) C-1054T (rs2031920) and 96-bp I/D genetic variations with the risk of polycystic ovary syndrome (PCOS), and to estimate the effects of genotypes on the clinical, metabolic, hormonal, and oxidative stress indicators. METHODS: This case-control study included 762 control women and 1034 patients with PCOS. Genotypes were determined using polymerase chain reaction and/or restriction fragment length polymorphism analysis. Clinical and biochemical parameters were also analyzed. RESULTS: Frequencies of the TT + CT genotype (35.4 vs. 28.9%) and T allele (19.6 vs. 16.0%) of the CYP2E1 C-1054T polymorphism were significantly higher in the PCOS group than in the control group (OR = 1.350, 95% CI 1.103-1.652, P = 0.004 for the dominant model). Genotype TT + CT remained a significant predictor of PCOS in a logistic regression model including age, body mass index (BMI), and recruitment year of participants (OR = 1.345, 95% CI 1.071-1.688, P = 0.011). No statistical differences were found in the genotype and allele frequencies of CYP2E1 96-bp I/D polymorphism. However, the combined genotype DD/TT + CT was related to an increased risk of PCOS when the DD/CC wild-type combined genotype was used as a reference. Patients with the I allele of 96-bp I/D polymorphism had a lower BMI but higher plasma apolipoprotein B and oxidized low-density lipoprotein cholesterol levels than those with the DD genotype. CONCLUSION: CYP2E1 C-1054T, but not 96-bp I/D, genetic polymorphism is associated with an increased risk of PCOS in Chinese women.

Tree shrew cytochrome P450 2E1 is a functional enzyme that metabolises chlorzoxazone and p-nitrophenol.

Cytochromes P450 (CYPs or P450s) are important enzymes for drug metabolism. Tree shrews are non-primate animal species used in various fields of biomedical research, including infection (especially hepatitis viruses), depression, and myopia. A recent tree shrew genome analysis indicated that the sequences and the numbers of P450 genes are similar to those of humans; however, P450s have not been adequately identified and analysed in this species.In this study, a novel CYP2E1 was isolated from tree shrew liver and was characterised in comparison with human, dog, and pig CYP2E1. Tree shrew CYP2E1 and human CYP2E1 showed high amino acid sequence identity (83%) and were closely related in a phylogenetic tree.Gene and genome structures of CYP2E1 were generally similar in humans, dogs, pigs, and tree shrews. Tissue expression patterns showed that tree shrew CYP2E1 mRNA was predominantly expressed in liver, just as for dog and pig CYP2E1 mRNAs. In tree shrews, recombinant CYP2E1 protein and liver microsomes metabolised chlorzoxazone and p-nitrophenol, probe substrates of human CYP2E1, just as they do in dogs and pigs.These results suggest that tree shrew CYP2E1 encodes a functional drug-metabolising enzyme that plays a role in the liver, similar to human CYP2E1.

Transgenic Zebrafish Expressing Rat Cytochrome P450 2E1 (CYP2E1): Augmentation of Acetaminophen-Induced Toxicity in the Liver and Retina.

Metabolic activation is the primary cause of chemical toxicity including hepatotoxicity. Cytochrome P450 2E (CYP2E) is involved in this process for many hepatotoxicants, including acetaminophen (APAP), one of the most common analgesics and antipyretics. Although the zebrafish is now used as a model for toxicology and toxicity tests, the CYP2E homologue in zebrafish has not been identified yet. In this study, we prepared transgenic zebrafish embryos/larvae expressing rat CYP2E1 and enhanced green fluorescent protein (EGFP) using a ß-actin promoter. Rat CYP2E1 activity was confirmed by the fluorescence of 7-hydroxycoumarin (7-HC), a metabolite of 7-methoxycoumarin that was specific for CYP2 in transgenic larvae with EGFP fluorescence (EGFP [+]) but not in transgenic larvae without EGFP fluorescence (EGFP [-]). APAP (2.5 mM) caused reduction in the size of the retina in EGFP [+] larvae but not in EGFP [-] larvae, while APAP similarly reduced pigmentation in both larvae. APAP at even 1 mM reduced the liver size in EGFP [+] larvae but not in EGFP [-] larvae. APAP-induced reduction of liver size was inhibited by N-acetylcysteine. These results suggest that rat CYP2E1 is involved in some APAP-induced toxicological endpoints in the retina and liver but not in melanogenesis of the developing zebrafish.

Generation and Characterization of CYP2E1-Overexpressing HepG2 Cells to Study the Role of CYP2E1 in Hepatic Hypoxia-Reoxygenation Injury.

The mechanisms of hepatic ischemia/reperfusion (I/R) injury, which occurs during liver transplantation or surgery, are poorly understood. The purpose of the current study was to generate and characterize a HepG2 cell line with a stable overexpression of CYP2E1 to investigate the role of the enzyme in hypoxia/reperfusion (H/R) injury in an ex vivo setting. GFP-tagged CYP2E1 and control clones were developed, and their gene expression and protein levels of GFP and CYP2E1 were determined using RT-PCR and ELISA/Western blot analysis, respectively. Additionally, the CYP2E1 catalytic activity was determined by UPLC-MS/MS analysis of 6-hydroxychlorzoxazone formed from the chlorzoxazone substrate. The CYP2E1 and control clones were subjected to hypoxia (10 h) and reoxygenation (0.5 h), and cell death and reactive oxygen species (ROS) generation were quantitated using LDH and flow cytometry, respectively. Compared with the control clone, the selected CYP2E1 clone showed a 720-fold increase in CYP2E1 expression and a prominent band in the western blot analysis, which was associated with a 150-fold increase in CYP2E1 catalytic activity. The CYP2E1 clone produced 2.3-fold more ROS and 1.9-fold more cell death in the H/R model. It is concluded that the constitutive CYP2E1 in the liver may play a detrimental role in hepatic I/R injury.

Chronotoxicity of Acrylamide in Mice Fed a High-Fat Diet: The Involvement of Liver CYP2E1 Upregulation and Gut Leakage.

Acrylamide (ACR) is produced under high-temperature cooking of carbohydrate-rich foods via the Maillard reaction. It has been reported that ACR has hepatic toxicity and can induce liver circadian disorder. A high fat diet (HFD) could dysregulate liver detoxification. The current study showed that administration of ACR (100 mg/kg) reduced the survival rate in HFD-fed mice, which was more pronounced when treated during the night phase than during the day phase. Furthermore, ACR (25 mg/kg) treatment could cause chronotoxicity in mice fed a high-fat diet, manifested as more severe mitochondrial damage of liver during the night phase than during the day phase. Interestingly, HFD induced a higher CYP2E1 expressions for those treated during the night phase, leading to more severe DNA damage. Meanwhile, the expression of gut tight junction proteins also significantly decreases at night phase, leading to the leakage of LPSs and exacerbating the inflammatory response at night phase. These results indicated that a HFD could induce the chronotoxicity of ACR in mice liver, which may be associated with increases in CYP2E1 expression in the liver and gut leak during the night phase.

Elucidation of Natural Components of Gardenia thunbergia Thunb. Leaves: Effect of Methanol Extract and Rutin on Non-Alcoholic Fatty Liver Disease.

The rising prevalence of non-alcoholic fatty liver disease NAFLD has strained the healthcare system. Natural products could solve this problem, so the current study focused on the impact of G. thunbergia Thunb. against this ailment. LC-ESI-MS/MS revealed the phytochemical profile of the methanol extract from Gardenia thunbergia leaves (GME). Forty-eight compounds were tentatively identified, and stigmasterol, fucosterol, ursolic acid, and rutin were isolated. The separation of the last three compounds from this plant had not before been achieved. The anti-NAFLD effect of the methanol extract of the leaves of G. thunbergia, and its major metabolite, rutin, was assessed in mice against high-fructose diet (HFD)-induced obesity. Male mice were allocated into nine groups: (1) saline (control), (2) 30% fructose (diseased group), (3) HFD, and 10 mg/kg of simvastatin. Groups 4-6 were administered HFD and rutin 50, 75, and 100 mg/kg. Groups (7-9) were administered HFD and methanol extract of leaves 100, 200, and 300 mg/kg. Methanol extract of G. thunbergia leaves at 200 mg/kg, and rutin at 75 mg/kg significantly reduced HFD-induced increments in mice weight and hepatic damage indicators (AST and ALT), steatosis, and hypertrophy. The levels of total cholesterol, LDL-C, and triglycerides in the blood decreased. In addition, the expressions of CYP2E1, JNK1, and iNOS in the diseased mice were downregulated. This study found that GME and rutin could ameliorate NAFLD in HFD-fed mice, with results comparable to simvastatin, validating G. thunbergia's hepatoprotective effects.

Racing against time: leveraging preclinical models to understand pulmonary susceptibility to perinatal acetaminophen exposures.

Over the past decade, clinicians have increasingly prescribed acetaminophen (APAP) for patients in the neonatal intensive care unit (NICU). Acetaminophen has been shown to reduce postoperative opiate burden, and may provide similar efficacy for closure of the patent ductus arteriosus (PDA) as nonsteroidal anti-inflammatory drugs (NSAIDs). Despite these potential benefits, APAP exposures have spread to increasingly less mature infants, a highly vulnerable population for whom robust pharmacokinetic and pharmacodynamic data for APAP are lacking. Concerningly, preclinical studies suggest that perinatal APAP exposures may result in unanticipated adverse effects that are unique to the developing lung. In this review, we discuss the clinical observations linking APAP exposures to adverse respiratory outcomes and the preclinical data demonstrating a developmental susceptibility to APAP-induced lung injury. We show how clinical observations linking perinatal APAP exposures to pulmonary injury have been taken to the bench to produce important insights into the potential mechanisms underlying these findings. We argue that the available data support a more cautious approach to APAP use in the NICU until large randomized controlled trials provide appropriate safety and efficacy data.